Calves infected with Mycoplasma bovis can develop pneumonia, middle ear disease, resulting in a head tilt, and arthritis with resultant reduced growth. In addition to these clinical signs, affected adult cattle can also develop mastitis.
With limited knowledge available on the distribution of M. bovis throughout Scotland and how it may be spreading within and between farms, the Veterinary Services team at Scotland’s Rural College is looking for Scottish dairy farms to participate in a year-long study consisting of bulk tank milk sampling and a short questionnaire on general herd management.
Throughout the project, participating farms will be provided with their own results via their registered veterinary practice.
M. bovis is spread between animals via a number of routes, with the most common being direct contact with an infected individual animal. Infection is also spread in the milking parlour, in bedding and in feeding equipment, and there is evidence that milk and colostrum from infected cows is also a source of infection to calves. Recently, semen from infected bulls has also been identified as a possible route of spread.
A unique feature of M. bovis is the absence of a cell wall, which means that some commonly used antibiotics, such as penicillin, don’t work. M. bovis can also alter its structure, allowing it to evade the cow’s immune system.
Animals which recover from infection may become carriers of the pathogen. The existence of this carrier state is poorly understood, as these animals will show no symptoms but have the ability to spread infection to others.
Maintaining high biosecurity by operating a closed herd will limit the risk of bringing M. bovis into the herd. Pasteurising cows’ milk and colostrum before feeding it to calves has been shown to significantly reduce the spread of M. bovis within a herd, as has disinfecting the milking parlour and feeding equipment.
Project lead Jessica Ireland-Hughes, from SRUC Veterinary Services, said: “This project will be of huge benefit to the industry as we currently don’t know how many farms have ongoing M. bovis-associated disease and which farms are more or less at risk.
“There is currently no national control scheme in place for this disease, and the results of this project will help develop more structured control plans to limit spread between and within herds, help manage the welfare and economic effects and reduce the reliance on antimicrobials.”
All Scottish dairy farmers will receive a flyer in the post from the Scottish Dairy Hub in the next week with details on how to get involved.
Email to mycoplasmabovis@sruc.ac.uk to find out more.
